1. Field of the Invention
The present invention relates to an object filtering method and a client device using the same and particularly, to a method for filtering an object to a client by a proxy server and a client device using the same.
2. Description of the Related Art
At present, WAP (Wireless Application Protocol) has been known as a network connecting protocol for cellular phones. If a user uses a WAP-supporting telephone, he/she could access to the Internet or the like from a portable terminal such as a cellular phone or the like by a simple operating method, and thus could utilize an electronic mail and other contents.
Various considerations have been made on this protocol in the WAP forum, and the latest versions of WAP are on public view in associated WEB sites. According to the specification titled “WAG UAPROF Version Nov. 10, 1999 (Wireless Application Group User Agent Profile Specification)” of the above WAP latest versions, it is provided that parameters indicating the WAP content processing capability of a WAP client and a desired Content format are transmitted as CPI (Capability and Preference Information) to a WAP gateway when a session is established between the WAP client and the WAP gateway and also the parameters are cached at all times when the session is established.
Further, according to this specification, it is also provided that CPI can be renewed by the WAP terminal as occasion demands. In the WAP gateway or the WAP origin server, the types of contents or objects to be transmitted to WAP clients can be restricted by using information of CPI.
CPI can represent various types of characteristics on WAP clients for clients such as hardware characteristics of WAP clients (display size, color support ability or disability, image support ability or disability, maker names, etc.), software characteristic (OS (Operating System)) vendors or versions, MExE support ability or disability, information on audio encoders, information on video encoders, etc.), application characteristics/user request matters (the makers of browsers, versions of browsers, characteristics of description language, versions of description language, script-based language support ability or disability, etc.), WAP characteristics (bearer characteristics, etc.), etc.
As disclosed in Japanese Patent No. 2893019, a technique of efficiently performing object distribution in a push service is known as a technique of filtering objects.
In the conventional object filtering technique as described above, when a proxy server transmits an object to a client in response to a client's object acquiring request, the object can be transmitted to the client with being subjected to filtering in accordance with the capability of the client by referring CPI.
However, the object is transmitted to the client irrespective of variation of the residual amount of the memory capacity in the client. Therefore, when the residual amount of the memory capacity is reduced and thus the overall content of a new object cannot be stored, the client is required to discard the object without storing it or delete some old objects to store a newly received object.
If the client discards the received object without storing it, there would occur such a disadvantage that communication resources between the proxy server and the client are wasted. On the other hand, if the old objects are deleted to store new objects, there would occur such a disadvantage that an important object is carelessly deleted.